Surgical robot driving mechanism

ABSTRACT

A surgical robot comprising a surgical robot arm and a surgical instrument. The surgical robot arm terminates at its distal end in a drive assembly comprising a first drive interface element. The surgical instrument comprises a shaft, an articulation attached to the distal end of the shaft, and a driving mechanism at the proximal end of the shaft. The articulation is for articulating an end effector, the articulation driveable by at least a first driving element and a second driving element. The driving mechanism comprises a first instrument interface element to which the first driving element is connected and a second instrument interface element to which the second driving element is connected. The first drive interface element engages both the first and second instrument interface elements such that: when the first drive interface element moves linearly, both the first and second instrument interface elements move in the same linear direction thereby driving both the first and second driving elements in the same direction; and when the first drive interface element rotates, the first and second instrument interface elements move reciprocally in opposing linear directions thereby driving the first and second driving elements in opposing directions.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 371 as a nationalstage application of PCT Application No. PCT/GB2016/051469, filed May20, 2016, which claims priority to GB 1508813.1, filed May 22, 2015,each of which is hereby incorporated herein by reference in itsentirety.

BACKGROUND

It is known to use robots for assisting and performing surgery. Surgicalrobots normally consist of a base, an arm, and an instrument. The basesupports the robot, and is itself attached rigidly to, for example, theoperating theatre floor, the operating theatre ceiling or a trolley. Thearm extends between the base and the instrument. The arm typically has aplurality of articulations, which are used to locate the surgicalinstrument in a desired location relative to the patient. The surgicalinstrument is attached to the distal end of the robot arm. The surgicalinstrument penetrates the body of the patient at a port so as to accessthe surgical site.

FIG. 1 illustrates a typical surgical instrument 100 for performingrobotic laparoscopic surgery. The surgical instrument comprises a base101 by which the surgical instrument connects to the robot arm. A shaft102 extends between base 101 and articulation 103. Articulation 103terminates in an end effector 104. In FIG. 1, a pair of serrated jawsare illustrated as the end effector 104. The articulation 103 permitsthe end effector 104 to move relative to the shaft 102. It is desirablefor at least two degrees of freedom to be provided to the motion of theend effector 104 by means of the articulation.

FIG. 2 illustrates an example of a known cabling arrangement 200 in asurgical instrument for transferring drive from the base of the surgicalinstrument 101 through the shaft 102 to the articulation 103. Cable pairC1, C2 terminate in the articulation as a loop around capstan 202. Theythen pass as a pair around one side of capstan 201. From there, thecable pair C1, C2 passes over capstan 204 and down through shaft 102 tothe base of the instrument 101. Cable pair C3, C4 terminate in thearticulation as a loop around capstan 203. They then pass as a pairaround the other side of capstan 201 to C1, C2. From there, the cablepair C3, C4 passes under capstan 204 and down through shaft 102 to thebase of the instrument 101. Rotation of yoke 205 about capstan 204causes the articulation 103 and hence the end effector 104 to pitchabout the capstan 204. Pitching in one direction is enabled by pullingcable pair C1, C2 and releasing cable pair C3, C4. Pitching in the otherdirection is enabled by pulling cable pair C3, C4 and releasing cablepair C1, C2. Rotation of capstan 202 causes one jaw of end effector 104to move. Movement in one direction is enabled by pulling cable C1 andreleasing cable C2. Movement in the other direction is enabled bypulling cable C2 and releasing cable C1. Rotation of capstan 203 causesthe other jaw of end effector 104 to move. Movement in one direction isenabled by pulling cable C3 and releasing cable C4. Movement in theother direction is enabled by pulling cable C4 and releasing cable C3.

Cables C1, C2, C3 and C4 are driven individually and independently bydrivers D1, D2, D3 and D4 respectively. These drivers are typicallylocated in the robot arm, and their drive is transmitted to the surgicalinstrument via an interface between the robot arm and the surgicalinstrument. A known interface plate is shown in FIG. 3. Spools 301, 302,303 and 304 are used to transfer the drive from the robot arm to thesurgical instrument. Drivers D1, D2, D3 and D4 in the robot arm providedrive to four cables in the robot arm which terminate at complimentaryspool features to the spools 301, 302, 303 and 304. These complimentaryspool features lock on to the spools 301, 302, 303, 304 such that arotation of a complimentary spool feature causes a correspondingrotation of the spool to which it is locked. On the opposite side of theinterface place, cables C1, C2, C3 and C4 terminate at complimentaryspool features to the spools 301, 302, 303 and 304. The complimentaryspool features lock onto the opposite sides of spools 301, 302, 303 and304 such that a rotation of a spool causes a corresponding rotation ofthe complimentary spool feature to which it is locked. Thus, drive istransferred from drivers D1, D2, D3 and D4 to cables C1, C2, C3 and C4.

The interfacing arrangement illustrated in FIG. 3 is complex, andrequires many precisely made components, which need to be aligned andlocked together accurately in the operating theatre. Every time aninstrument is replaced during an operation, the instrument must bedetached from the interface plate, and another instrument accuratelyaligned and locked into the interface plate in order to enable theinstrument to be used.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a surgicalrobot arm terminating at its distal end in a drive assembly for drivinga surgical instrument, the surgical instrument having an articulationfor articulating an end effector, the articulation driveable by at leasta first driving element and a second driving element, the drive assemblycomprising: a first drive interface element configured to engage with afirst instrument interface element for coupling drive to the firstdriving element and a second instrument interface element for couplingdrive to the second driving element, wherein the first drive interfaceelement is permitted to: move linearly so as to cause the first andsecond instrument interface elements to move in the same directionthereby driving both the first and second driving elements in the samedirection; and rotate so as to cause reciprocal motion of the first andsecond instrument interface elements in opposing directions therebydriving the first and second driving elements in opposing directions.

Suitably, the first drive interface element is permitted to rotate aboutan axis disposed halfway between where the first drive interface elementengages with the first instrument interface element and where the firstdrive interface element engages with the second instrument interfaceelement, such that rotation of the first drive interface element causeslinear motion of the first instrument interface element in one directionand a matching linear motion of the second instrument interface elementin an opposing direction.

The first drive interface element may be permitted to move linearlyalong a longitudinal axis of the proximal end of the shaft.

Suitably, the first drive interface element is permitted to rotate aboutan axis perpendicular to a longitudinal axis of the proximal end of theshaft.

The first drive interface element may be rigid.

The first drive interface element may comprise two arms configured toembrace the first and second instrument interface elements.

The first drive interface element may be U-shaped.

The drive assembly may further comprise a second drive interface elementconfigured to engage with a third instrument interface element forcoupling drive to a third driving element and a fourth instrumentinterface element for coupling drive to a fourth driving element,wherein the second drive interface element is permitted to: movelinearly so as to cause the third and fourth instrument interfaceelements to move in the same direction thereby driving both the thirdand fourth driving elements in the same direction; and rotate so as tocause reciprocal motion of the third and fourth instrument interfaceelements in opposing directions thereby driving the third and fourthdriving elements in opposing directions.

The drive assembly may be configured to move the first drive interfaceelement and the second drive interface element independently of eachother.

According to a second aspect of the invention, there is provided arobotic surgical instrument comprising: a shaft; an articulationattached to the distal end of the shaft, the articulation forarticulating an end effector, the articulation driveable by at least afirst driving element and a second driving element; and a drivingmechanism at the proximal end of the shaft, the driving mechanismcomprising: a first slideable unit to which the first driving element issecured, and a second slideable unit to which the second driving elementis secured, wherein the first and second slideable units are permittedto slide linearly relative to each other; a first instrument interfaceelement connected to the first slideable unit, and a second instrumentinterface element connected to the second slideable unit, both the firstand second instrument interface elements configured to engage with afirst drive interface element of a drive assembly such that the firstand second instrument interface elements are driveable in the samelinear direction so as to drive both the first and second drivingelements in the same direction, and the first and second instrumentinterface elements are driveable in opposing linear directions so as todrive the first and second driving elements in opposing directions.

The first and second slideable units may be stacked such that theirlongitudinal axes are parallel, and the first and second slideable unitsare permitted to slide parallel to their longitudinal axes.

The first instrument interface element may be a first rod protrudingfrom the first slideable unit in a direction transverse to thelongitudinal axis of the first slideable unit, and the second instrumentinterface element may be a second rod protruding from the secondslideable unit in a direction transverse to the longitudinal axis of thesecond slideable unit.

The first and second rods may be parallel.

Suitably, in a configuration in which the articulation is de-tensioned,the first and second rods are aligned along an axis transverse to thelongitudinal axes of the first and second slideable units and transverseto the longitudinal axes of the first and second rods.

The first and second rods may each be encompassed in a foam roller, eachfoam roller configured to engage with the first drive interface element.

Suitably, the articulation is additionally driveable by a third drivingelement and a fourth driving element; and wherein the driving mechanismfurther comprises: a third slideable unit to which the third drivingelement is secured, and a fourth slideable unit to which the fourthdriving element is secured, wherein the first, second, third and fourthslideable units are permitted to slide linearly relative to each other;a third instrument interface element connected to the third slideableunit, and a fourth instrument interface element connected to the fourthslideable unit, both the third and fourth instrument interface elementsconfigured to engage with a second drive interface element of the driveassembly such that the third and fourth instrument interface elementsare driveable in the same linear direction so as to drive both the thirdand fourth driving elements in the same direction, and the third andfourth instrument interface elements are driveable in opposing lineardirections so as to drive the third and fourth and elements in opposingdirections.

Suitably, the first, second, third and fourth slideable units arestacked such that their longitudinal axes are parallel, and the first,second, third and fourth slideable units are permitted to slide relativeto each other parallel to their longitudinal axes. The first, second,third and fourth slideable units may be stacked in a 2×2 configuration,such that the first and second instrument interface elements are on anopposing face of the configuration as the third and fourth instrumentinterface elements.

Suitably, the articulation is a wrist articulation comprising a pitchjoint which is configured to pitch the wrist articulation, the first,second, third and fourth driving elements being connected to the wristarticulation such that: when the first and second slideable units aredisplaced linearly in a first direction by the first drive interfaceelement, and the third and fourth slideable units are displaced linearlyin the opposing direction by the second drive interface element, thewrist articulation pitches in one direction about the pitch joint; andwhen the first and second slideable units are displaced linearly in theopposing direction by the first drive interface element, and the thirdand fourth slideable units are displaced linearly in the first directionby the second drive interface element, the wrist articulation pitches inthe opposing direction about the pitch joint.

Suitably, the articulation comprises a joint configured to actuateopposing first and second jaws of an end effector, the first and seconddriving elements being connected to the joint such that when the firstand second slideable units are displaced linearly in opposing directionsby the first drive interface element, the first jaw rotates in onedirection about the joint, and when the first drive interface elementapplies a drive in an opposing direction the first jaw rotates in anopposing direction about that joint.

The third and fourth driving elements may be connected to the joint suchthat when the third and fourth slideable units are displaced linearly inopposing directions by the second drive interface element, the secondjaw rotates in one direction about the joint, and when the second driveinterface element applies a drive in an opposing direction the secondjaw rotates in an opposing direction about that joint.

The driving elements may be elongate and flexible. The driving elementsmay be cables. The driving elements may resist compression and tensionforces.

According to a third aspect of the invention, there is provided asurgical robot comprising: a surgical robot arm terminating at itsdistal end in a drive assembly, the drive assembly comprising a firstdrive interface element; and a surgical instrument comprising: a shaft;an articulation attached to the distal end of the shaft, thearticulation for articulating an end effector, the articulationdriveable by at least a first driving element and a second drivingelement; and a driving mechanism at the proximal end of the shaft, thedriving mechanism comprising a first instrument interface element towhich the first driving element is connected and a second instrumentinterface element to which the second driving element is connected;wherein the first drive interface element engages both the first andsecond instrument interface elements such that: when the first driveinterface element moves linearly, both the first and second instrumentinterface elements move in the same linear direction thereby drivingboth the first and second driving elements in the same direction; andwhen the first drive interface element rotates, the first and secondinstrument interface elements move reciprocally in opposing lineardirections thereby driving the first and second driving elements inopposing directions.

A covering may be disposed over the driving mechanism so as to provide asterile barrier between the instrument interface elements and the driveinterface elements.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will now be described by way of example withreference to the accompanying drawings. In the drawings:

FIG. 1 illustrates a known surgical instrument;

FIG. 2 illustrates a known cabling arrangement of a surgical instrument;

FIG. 3 illustrates a known interface plate for interfacing a surgicalrobot arm and a surgical instrument;

FIGS. 4a, 4b and 4c illustrate a driving mechanism at the end of thesurgical instrument distal from the end effector and an interface ofthat driving mechanism with a drive assembly of the robot arm;

FIG. 5 illustrates an exemplary mechanism for coupling drive to thedrive interface elements of the drive assembly of FIGS. 4a, 4b and 4c ;and

FIGS. 6a, 6b and 6c illustrate the components of FIGS. 4a, 4b and 4c asapplied in an articulated surgical instrument.

DETAILED DESCRIPTION

FIG. 4a illustrates a schematic drawing of an exemplary drivingmechanism 400 of the interior of a robotic surgical instrument at theend of the surgical instrument distal from the end effector, and theinterface of this driving mechanism with the drive assembly of asurgical robot arm. The surgical instrument as a whole has the generalform shown in FIG. 1. In other words, the surgical instrument comprisesa base 101 by which the surgical instrument connects to the surgicalrobot arm. The instrument base is designed cooperatively with theterminal end of the surgical robot arm, such that the instrument base isreleasably attachable to the terminal end of the robot arm. A shaft 102extends between the base 101 and an articulation 103. The articulation103 is connected at its proximal end to the shaft 102 and at its distalend to an attachment suitable for attaching an end effector 104. Theshaft 102 and articulation 103 are all hollow. This allows passage ofelements up these sections to actuate the end effector 104. It alsoreduces the weight of the surgical instrument.

The end effector may take any suitable form. For example, the endeffector may be smooth jaws, serrated jaws, a gripper, a pair of shears,a needle for suturing, a camera, a laser, a knife, a stapler, acauteriser, a suctioner.

The driving mechanism of FIG. 4a is arranged to drive two pairs ofdriving elements, E1, E2 and E3, E4. The driving elements may, forexample, be cables.

The driving mechanism of FIG. 4a comprises a set of slideable units.Driving element E1 terminates in slideable unit 401, driving element E2terminates in slideable unit 402, driving element E3 terminates inslideable unit 403, and driving element E4 terminates in slideable unit404. Each driving element is secured to the end of its slideable unitwhich is closest to the distal end of the shaft at which thearticulation and end effector are located.

In FIG. 4a , the slideable units are blocks which are stacked such thattheir longitudinal axes 405, 406, 407 and 408 are parallel. Theslideable units are permitted to slide linearly relative to each other.Suitably, the slideable units are permitted to slide parallel to theirlongitudinal axes. In FIG. 4a , the slideable units are depicted as eachhaving a cuboid shape. Suitably, the slideable units have matchingshapes and sizes. It will be understood that the slideable units mayhave any suitable shape that enables them to slide linearly relative toeach other.

The first and second slideable units 401 and 402 are stacked such thatat least one side of slideable unit 401 is flush with one side ofslideable unit 402. Similarly, the third and fourth slideable units 103and 404 are stacked such that at least one side of slideable unit 403 isflush with one side of slideable unit 404. FIG. 4a illustrates slideableunits 401 and 402 to be stacked on top of each other, and slideableunits 403 and 404 to be stacked on top of each other, and slideable unitpair 401, 402 to be stacked side-by-side with slideable unit pair 403,404 so as to form a 2×2 configuration in which longitudinal faces of theunits are facing each other. Alternatively, the 2×2 configuration may besuch that the short faces of slideable unit pair 401, 402 are facing theshort faces of slideable unit pair 403, 404.

The longitudinal axes of the slideable units 405, 406, 407 and 408 areparallel to the longitudinal axes of the driving elements to which theyare attached. Thus, linear movement of a slideable unit along itslongitudinal axis causes the driving element to which it is connected tobe tensioned or compressed along the longitudinal axis of the drivingelement. Suitably, both the longitudinal axes of the slideable units andthe longitudinal axes of the driving elements are parallel to thelongitudinal axis of the instrument shaft.

Each slideable unit of a slideable unit pair is permitted to movelinearly in the same direction as the other slideable unit of theslideable unit pair. For example, FIG. 4b illustrates a configuration inwhich both slideable units 403 and 404 have moved in the direction ofthe arrow marked 409, and both slideable units 401, 402 have moved inthe opposite direction, i.e. in the direction of the arrow marked 410.This thereby causes driving elements E3 and E4 to be tensioned, anddriving elements E1 and E2 to be relaxed or compressed.

Each slideable unit of a slideable unit pair is permitted to movelinearly in an opposing direction as the other slideable unit of theslideable unit pair. For example, FIG. 4c illustrates a configuration inwhich slideable unit 404 has moved in the direction of the arrow marked409, and slideable unit 403 has moved in the opposite direction, i.e. inthe direction of the arrow marked 410. This thereby causes drivingelement E4 to be tensioned, and driving element E3 to be relaxed orcompressed.

An instrument interface element is connected to each slideable unit. Theinstrument interface element is configured to engage with acomplimentary interface component of the robot arm, so as to enable therobot arm to selectively move the slideable units linearly, and therebycouple drive to the driving elements.

In FIG. 4a , each interface element is a rod 411, 412 protruding fromthe slideable unit. The rod is rigidly attached to the slideable unit.Thus, movement of the rod causes the slideable unit to move. The rodprotrudes from the slideable unit in a direction transverse to thelongitudinal axis of the slideable unit. The longitudinal axis of therod 413, 414 is perpendicular to the longitudinal axis of the slideableunit 407, 408. The two rods which protrude from the slideable unit pair401, 402 are parallel. The two rods which protrude from the slideableunit pair 403, 404 are parallel. Suitably, the rods protruding from allthe slideable units are parallel to each other. In the example of FIG.4a , the rods protruding from the slideable unit pair 401, 402 are onthe opposing face of the 2×2 configuration than the rods protruding fromthe slideable unit pair 403, 404.

FIG. 4a illustrates a configuration of the driving mechanism in whichthe driving elements are at rest. In other words, none of the drivingelements is being tensioned in the configuration of FIG. 4a . In thisconfiguration, the centres of rod 411 of slideable unit 403 and rod 412of slideable unit 404 are aligned along an axis 415 transverse to thelongitudinal axes of the slideable units 403 and 404 and transverse tothe longitudinal axes 413 and 414 of the rods 411 and 412. The rods ofslideable units 401 and 402 are correspondingly aligned.

In the example of FIG. 4a , each rod is encompassed by a foam roller416, 417. The foam roller engages with the interface element of therobot arm.

The drive assembly of the robot arm interfaces with the drivingmechanism of the instrument via drive interface elements 418, 419. Driveinterface element 418 engages the instrument interface elements ofslideable units 403 and 404. Drive interface element 419 engages theinstrument interface elements of slideable units 401 and 402. Driveinterface element 419 acts on the slideable units 401 and 402 in thesame way that drive interface element 418 acts on the slideable units403 and 404. Thus, only drive interface element 418 is described in thefollowing, and that description understood to apply correspondingly todrive interface element 419.

Drive interface element 418 engages both instrument interface element411 of slideable unit 403 and the instrument interface element 412 ofslideable unit 404. The drive interface element 418 in the example ofFIG. 4a is a rigid, U-shaped structure. The arms 420 and 421 of thestructure embrace both the rod 411 and the rod 412 equally in FIG. 4a .Each arm 420, 421 is in contact with both the instrument interfaceelements 411, 412.

The drive interface element 418 is permitted to move linearly along thelongitudinal axes 407, 408 of the slideable units 403, 404. Suchmovement is illustrated in FIG. 4b . The whole of the drive interfaceelement 418 has been displaced linearly in the direction 409 relative toFIG. 4a . The embrace of drive interface element 418 around theinstrument interface elements is tight, thus movement of the driveinterface element 418 causes movement of the instrument interfaceelements and hence the slideable units 403, 404. When the driveinterface element 418 is displaced linearly in the direction 409, bothof the slideable units 403, 404 are also both linearly displaced in thedirection 409. The slideable units 403, 404 are both subject to the samedisplacement. This causes driving elements E3 and E4, which are rigidlysecured to slideable units 403, 404, to be tensioned.

The drive interface element 418 is permitted to rotate about an axis422. Axis 422 is perpendicular to the longitudinal axes 407 and 408 ofslideable units 403 and 404. Axis 422 is parallel to the longitudinalaxes 413, 414 of the rods 411, 412 and intersects the line between thecentres of the rods 411, 412 halfway between the centres of the rods411, 412. FIG. 4c illustrates an anticlockwise rotation of the driveinterface element 418 about its rotation axis 413 relative to FIG. 4a .This rotation has caused slideable unit 403 to move in the lineardirection 410 and slideable unit 404 to move in the linear direction409. The motion of slideable unit 403 is reciprocal to the motion ofslideable unit 404. Slideable unit 404 has been displaced in the lineardirection 409 by the same amount that slideable unit 403 has beendisplaced in the opposing linear direction 410. This causes drivingelement E3 to be tensioned by the same magnitude that driving element E4is compressed.

The drive assembly is configured to move the drive interface element 418independently of the drive interface element 419. In FIG. 4c , the driveinterface element 418 has been rotated about its axis whilst the driveinterface element 419 has not been moved. In FIG. 4b , the driveinterface element 418 has been driven in an opposing linear direction tothe drive interface element 419.

Any suitable mechanism may be used to drive interface element 418 in themanner described above. FIG. 5 illustrates an exemplary drivingmechanism utilising two motor and lead screw arrangements. The firstmotor and lead screw arrangement 501 is attached to the drive interfaceelement to one side of where the drive interface element embraces thetwo instrument interface elements 411, 412. The second motor and leadscrew arrangement 502 is attached to the drive interface element to theother side of where the drive interface element embraces the twoinstrument interface elements 411, 412.

Motor and lead screw arrangement 501 comprises a shaft 503 rigidlysecured to arm 420 of drive interface element 418. The shaft 503 isparallel to the longitudinal axes 407 and 408 of the slideable units 403and 404. The shaft is secured to a plate 504. Motor 506 drives athreaded screw 505 through a complimentary threaded aperture in theplate 504. When the motor drives the screw 505 in one direction, theplate moves in the direction 409. Thus, the part of the drive interfaceelement 418 that the shaft 503 is secured to moves in the direction 409.When the motor drives the screw 505 in the opposing direction, the platemoves in the direction 410. Thus, the part of the drive interfaceelement 418 that the shaft is secured to moves in the direction 410. Thesecond motor and lead screw arrangement 502 works in the same manner.

The drive interface element 418 is moved from its position in FIG. 4a toits position in FIG. 4b by both motor and lead screw arrangements 501and 502 driving the screws in the same direction, so as to cause thedrive interface element 418, and hence the slideable units 403 and 404to move in the direction 409.

The drive interface element 418 is moved from its position in FIG. 4a toits position in FIG. 4c by the motor and lead screw arrangements 501 and502 driving their screws in opposing directions, such that the motor andlead screw arrangement 501 pushes the portion of the drive interfaceelement 418 that it is connected to in the direction 410, and such thatthe motor and lead screw arrangement 502 pulls the portion of the driveinterface element 418 that it is connected to in the direction 409,thereby causing the drive interface element 418 to rotate in acounter-clockwise direction about its axis 422.

FIG. 5 illustrates the motor and lead screw arrangements 501 and 502 asboth being attached to the same arm 420 of drive interface element 418.However, any arrangement of the motor and lead screw arrangements 501and 502 in which the whole of the drive interface element 418 can belinearly displaced and also rotated about its axis 422 may be used. Forexample, the motor and lead screw arrangements 501 and 502 may beattached to the other arm 421 of drive interface element 418. Or themotor and lead screw arrangements 501 and 502 may be attached toopposing ones of the arms 420 and 421.

Surgical drape 423 may be interposed between the robot arm and thesurgical instrument so as to provide a barrier between the sterileinstrument and the non-sterile robot arm. The surgical drape is locatedbetween the drive interface element 418 and the instrument interfaceelements.

FIGS. 6a, 6b and 6c illustrate configurations in which the driveassembly and driving mechanism of FIGS. 4a, 4b and 4c is used to drivean articulation 103 at the distal end of the instrument shaft 102.Articulation 103 is as described with reference to FIG. 2. Thearticulation comprises a plurality of joints for articulating an endeffector. The end effector comprises two opposing jaws. One of thesejaws is rigidly attached to capstan 202. The other jaw of the endeffector is rigidly attached to capstan 203. The joints of thearticulation 103 are driven by the driving element pairs E1, E2 and E3,E4 of FIGS. 6a, 6b and 6c . Driving element pairs E1, E2 and E3, E4engage the driving mechanism and drive assembly as described herein.Driving element pairs E1, E2, and E3, E4 extend through the hollow shaft102 to the articulation 103 at the distal end of the shaft. Drivingelement pairs E1, E2 and E3, E4 engage with the articulation 103 at thedistal end of the shaft as described with reference to FIG. 2, where E1and E2 correspond to C3 and C4, and E3 and E4 correspond to C1 and C2.

The articulation is a wrist articulation, which includes pitch joint204. Rotation about pitch joint 204 causes the wrist, and hence the endeffector 104, to pitch relative to the shaft 102. FIG. 6b illustratespitch joint 204 rotated relative to FIG. 6a in the direction marked 601.This is caused by tensioning driving element pair E3, E4 andde-tensioning or compressing driving element pair E1, E2. This isachieved by the drive assembly linearly displacing the drive interfaceelement 418 in the direction 409 away from the articulation 301, andlinearly displacing the drive interface element 419 in the direction 410towards the articulation 301. Suitably, the drive assembly linearlydisplaces the drive interface element 418 away from the distal end ofthe shaft, and linearly displaces the drive interface element 419towards the distal end of the shaft. Conversely, pitch joint 204 iscaused to rotate in the opposing direction marked 602 on FIG. 6b bytensioning driving element pair E1, E2 and de-tensioning or compressingdriving element pair E3, E4. This is achieved by the drive assemblylinearly displacing the drive interface element 418 in the direction 410towards the articulation 301, and linearly displacing the driveinterface element 419 in the direction 409 away from the articulation301. Suitably, the drive assembly linearly displaces the drive interfaceelement 418 towards the distal end of the shaft, and linearly displacesthe drive interface element 419 away from the distal end of the shaft.

Rotation about capstan 202 causes a first jaw of the end effector torotate about the central axis 603 of capstan 202. FIG. 6c illustrates arotation of the capstan 202 in the direction 604 such that the first jawis pointing in the direction indicated by arrow 606. The first jaw iscaused to rotate in the direction marked 604 by tensioning drivingelement E4 and de-tensioning or compressing driving element E3. This isachieved by drive assembly rotating drive interface element 418 aboutits axis 422 in an anticlockwise direction. In other words, the base ofthe U-shaped element 418 moves away from the articulation, and the topof the U-shaped element moves towards the articulation. Conversely, thefirst jaw is caused to rotate in the opposing direction marked 605 bytensioning driving element E3 and de-tensioning or compressing drivingelement E4. This is achieved by drive assembly rotating drive interfaceelement 418 about its axis 422 in a clockwise direction. In other words,the base of the U-shaped element 418 moves towards the articulation, andthe base of the U-shaped element moves away from the articulation. Thetension status of driving elements E1 and E2 are immaterial to drivingrotation of the first jaw about capstan 202. The motions of drivingelement pair E1, E2 and driving element pair E3, E4 are not coupled whendriving rotation about capstan 202.

Rotation about capstan 203 causes a second jaw of the end effector torotate about the central axis 607 of capstan 203. Central axis 607 ofcapstan 203 is parallel to central axis 603 of capstan 202. Suitably,central axis 607 of capstan 203 is collinear with central axis 603 ofcapstan 202. The second jaw is caused to rotate in the direction marked604 by tensioning driving element E2 and de-tensioning or compressingdriving element E1. This is achieved by drive assembly rotating driveinterface element 419 about its axis in an anticlockwise direction. Inother words, the base of the U-shaped element 419 moves away from thearticulation, and the top of the U-shaped element moves towards thearticulation. Conversely, the second jaw is caused to rotate in theopposing direction marked 605 by tensioning driving element E1 andde-tensioning or compressing driving element E2. This is achieved bydrive assembly rotating drive interface element 419 about its axis in aclockwise direction. In other words, the base of the U-shaped element419 moves towards the articulation, and the base of the U-shaped elementmoves away from the articulation. The tension status of driving elementsE3 and E4 are immaterial to driving rotation of the second jaw aboutcapstan 203. The motions of driving element pair E1, E2 and drivingelement pair E3, E4 are not coupled when driving rotation about capstan203.

The driving mechanism independently drives motion of pitch joint 204 andeach of the jaws by capstans 202 and 203. One or both jaws may beactuated concurrently with pitching the wrist by driving the drivingelements E1, E2, E3 and E4 as described above.

The driving elements E1, E2, E3 and E4 are flexible. Each drivingelement is elongate. Each driving element can be flexed laterally to itsmain extent. In other words, each driving element can be flexedtransversely to its longitudinal axis. Each driving element is notflexible along its main extent. Each driving element resists compressionand tension forces acting in the direction of its longitudinal axis.Thus, the driving elements are able to transfer drive from the proximalend of the instrument to the articulation. The driving elements may becables.

Each driving element illustrated in FIGS. 6a, 6b and 6c is rigidlysecured to the capstan about which it terminates in the articulation. InFIGS. 6a, 6b and 6c , driving element pair E1, E2 is rigidly fixed tocapstan 202 at the point on capstan 202 which is most distal to thedriving mechanism 400 and lies on the longitudinal axis of the shaftwhen the end effector, articulation and shaft are in the straightconfiguration shown in FIG. 6a . Similarly, in FIGS. 6a, 6b and 6c ,driving element pair E3, E4 is rigidly fixed to capstan 203 at the pointon capstan 203 which is most distal to the driving mechanism 400 andlies on the longitudinal axis of the shaft when the end effector,articulation and shaft are in the straight configuration shown in FIG. 6a.

In an alternative configuration, driving elements E1 and E2 may bedisconnected at the articulation. In other words, driving elements E1and E2 may not form a continuous element about the capstan 203. Instead,driving elements E1 and E2 may each individually terminate at capstan203, to which they are individually secured. Similarly, driving elementsE3 and E4 may be disconnected at the articulation. In other words,driving elements E3 and E4 may not form a continuous element about thecapstan 202. Instead, driving elements E3 and E4 may each individuallyterminate at capstan 202, to which they are individually secured.

Suitably, the longitudinal axis of the distal end of the robot arm iscollinear with the longitudinal axis of the shaft of the instrument. Andthe longitudinal axes of the slideable units are parallel to thelongitudinal axes of the distal end of the robot arm and the instrumentshaft.

It may be desirable for the driving mechanism to be located in adifferent orientation or location at the proximal end of the instrumentshaft in order to utilise the space in the central interior area of theinstrument shaft for other components. In this case, additional pulleysmay be used compared to FIGS. 4a, 4b and 4c to locate the drivingmechanism in the alternative orientation/location. This alternativeorientation/location may be such that the longitudinal axes of theslideable units are no longer parallel to the longitudinal axis of theinstrument shaft. The drive assembly displaces the drive interfaceelements 418, 419 linearly to the longitudinal axes of the slideableunits. However, this linear movement may no longer be parallel to thelongitudinal axis of the instrument shaft. However, by means of theadditional pulleys, the same motions of the driving elements in theshaft are achieved by driving the drive interface elements 418, 419.

FIGS. 6a, 6b and 6c illustrate the driving mechanism of FIGS. 4a, 4b and4c driving an articulation 103 at the distal end of the instrument shaft102. The driving mechanism of FIGS. 4a, 4b and 4c may be used to driveother configurations of articulation at the distal end of an instrumentshaft. The driving mechanism of FIGS. 4a, 4b and 4c can drive anyarticulation which is driveable with two pairs of driving elements whichare capable of transferring motion as described herein.

It will be appreciated that the drive assembly and the drivingmechanisms described herein could be modified to include further drivingelements to transfer drive to further joints of an articulation at thedistal end of the instrument shaft.

The driving mechanism described herein de-tensions the driving elementsE1, E2, E3 and E4 completely when the joint is in the straightconfiguration shown in FIG. 4 a.

In the interfacing arrangement described herein, the robot arminterfaces directly with the surgical instrument without using anintermediate interface plate. The driving mechanism slots easily intothe two U-shaped drive interface elements.

Suitably, the slideable units are fabricated from nylon. Suitably, thedrive interface elements are aluminium. Suitably, the drape isfabricated from polyester, polypropylene, polyethylene orpolytetrafluoroethylene.

The instrument could be used for non-surgical purposes. For example itcould be used in a cosmetic procedure.

The applicant hereby discloses in isolation each individual featuredescribed herein and any combination of two or more such features, tothe extent that such features or combinations are capable of beingcarried out based on the present specification as a whole in the lightof the common general knowledge of a person skilled in the art,irrespective of whether such features or combinations of features solveany problems disclosed herein, and without limitation to the scope ofthe claims. The applicant indicates that aspects of the presentinvention may consist of any such individual feature or combination offeatures. In view of the foregoing description it will be evident to aperson skilled in the art that various modifications may be made withinthe scope of the invention.

The invention claimed is:
 1. A surgical robot comprising: a surgicalrobot arm terminating at a distal end in a drive assembly, the driveassembly comprising a first drive interface element; and a surgicalinstrument comprising: a shaft; a first driving element and a seconddriving element; an articulation attached to a distal end of the shaft,the articulation configured to articulate an end effector, thearticulation driveable by at least the first driving element and thesecond driving element; and a driving mechanism at a proximal end of theshaft, the driving mechanism comprising a first instrument interfaceelement to which the first driving element is connected and a secondinstrument interface element to which the second driving element isconnected; wherein the first drive interface element engages both thefirst and second instrument interface elements such that: when the firstdrive interface element moves linearly, both the first and secondinstrument interface elements move in a same linear direction therebydriving both the first and second driving elements in the samedirection; and when the first drive interface element rotates, the firstand second instrument interface elements move reciprocally in opposinglinear directions thereby driving the first and second driving elementsin opposing directions.
 2. The surgical robot as claimed in claim 1,wherein the first drive interface element is permitted to rotate aboutan axis disposed halfway between where the first drive interface elementengages with the first instrument interface element and where the firstdrive interface element engages with the second instrument interfaceelement, such that rotation of the first drive interface element causeslinear motion of the first instrument interface element in one directionand a matching linear motion of the second instrument interface elementin an opposing direction.
 3. The surgical robot as claimed in claim 1,wherein the first drive interface element is permitted to move linearlyalong a longitudinal axis of the distal end of the surgical robot arm.4. The surgical robot as claimed in claim 1, wherein the first driveinterface element is permitted to rotate about an axis perpendicular toa longitudinal axis of the distal end of the surgical robot arm.
 5. Thesurgical robot as claimed in claim 1, wherein the first drive interfaceelement is rigid.
 6. The surgical robot as claimed in claim 1, whereinthe first drive interface element comprises two arms configured toembrace the first and second instrument interface elements.
 7. Thesurgical robot as claimed in claim 1, wherein the first drive interfaceelement is U-shaped.
 8. The surgical robot as claimed in claim 1,further comprising: a third driving element; a fourth driving element; athird instrument interface element coupled to the third driving element;and a fourth instrument interface element coupled to the fourth drivingelement, wherein the drive assembly further comprises a second driveinterface element configured to engage with the third instrumentinterface element for coupling drive to the third driving element andthe fourth instrument interface element for coupling drive to the fourthdriving element, wherein the second drive interface element is permittedto: move linearly so as to cause the third and fourth instrumentinterface elements to move in a same direction thereby driving both thethird and fourth driving elements in the same direction; and rotate soas to cause reciprocal motion of the third and fourth instrumentinterface elements in opposing directions thereby driving the third andfourth driving elements in opposing directions.
 9. The surgical robot asclaimed in claim 8, wherein the drive assembly is configured to move thefirst drive interface element and the second drive interface elementindependently of each other.
 10. The surgical robot as claimed in claim1, wherein the driving mechanism comprises: a first slideable unit towhich the first driving element is secured, and a second slideable unitto which the second driving element is secured, wherein the first andsecond slideable units are permitted to slide linearly relative to eachother and wherein the first instrument interface element is connected tothe first slideable unit, and the second instrument interface element isconnected to the second slideable unit.
 11. The surgical robot asclaimed in claim 10, wherein the first and second slideable units arestacked such that longitudinal axes of the first and second slideableunits are parallel, and the first and second slideable units arepermitted to slide parallel to their longitudinal axes.
 12. The surgicalrobot as claimed in claim 10, wherein the first instrument interfaceelement is a first rod protruding from the first slideable unit in adirection transverse to a longitudinal axis of the first slideable unit,and the second instrument interface element is a second rod protrudingfrom the second slideable unit in a direction transverse to alongitudinal axis of the second slideable unit.
 13. The surgical robotas claimed in claim 12, wherein in a configuration in which thearticulation is de-tensioned, the first and second rods are alignedalong an axis transverse to the longitudinal axes of the first andsecond slideable units and transverse to the longitudinal axes of thefirst and second rods.
 14. The surgical robot as claimed in claim 12,wherein the first and second rods are each encompassed in a foam roller,each foam roller configured to engage with the first drive interfaceelement.
 15. The surgical robot as claimed in claim 10, furthercomprising a third driving element and a fourth driving element and thearticulation is additionally driveable by the third driving element andthe fourth driving element; and wherein the driving mechanism furthercomprises: a second drive interface element; a third slideable unit towhich the third driving element is secured, and a fourth slideable unitto which the fourth driving element is secured, wherein the first,second, third and fourth slideable units are permitted to slide linearlyrelative to each other; and a third instrument interface elementconnected to the third slideable unit, and a fourth instrument interfaceelement connected to the fourth slideable unit, both the third andfourth instrument interface elements configured to engage with thesecond drive interface element of the drive assembly such that the thirdand fourth instrument interface elements are driveable in a same lineardirection so as to drive both the third and fourth driving elements inthe same direction, and the third and fourth instrument interfaceelements are driveable in opposing linear directions so as to drive thethird and fourth instrument interface elements in opposing directions.16. The surgical robot as claimed in claim 15, wherein the first,second, third and fourth slideable units are stacked in a 2×2configuration, such that the first and second instrument interfaceelements are on an opposing face of the 2×2 configuration from the thirdand fourth instrument interface elements.
 17. The surgical robot asclaimed in claim 15, wherein the articulation is a wrist articulationcomprising a pitch joint which is configured to pitch the wristarticulation, the first, second, third and fourth driving elements beingconnected to the wrist articulation such that: (i) when the first andsecond slideable units are displaced linearly in a first direction bythe first drive interface element, and the third and fourth slideableunits are displaced linearly in the opposing direction by the seconddrive interface element, the wrist articulation pitches in one directionabout the pitch joint; and (ii) when the first and second slideableunits are displaced linearly in the opposing direction by the firstdrive interface element, and the third and fourth slideable units aredisplaced linearly, in the first direction by the second drive interfaceelement, the wrist articulation pitches in the opposing direction aboutthe pitch joint.
 18. The surgical robot as claimed in claim 15, whereinthe articulation comprises a joint configured to actuate opposing firstand second jaws of an end effector, the first and second drivingelements being connected to the joint such that when the first andsecond slideable units are displaced linearly in opposing directions bythe first drive interface element, the first jaw rotates in onedirection about the joint, and when the first drive interface elementapplies a drive in an opposing direction the first jaw rotates in anopposing direction about that joint.
 19. The surgical robot as claimedin claim 18, wherein the third and fourth driving elements are connectedto the joint such that when the third and fourth slideable units aredisplaced linearly in opposing directions by the second drive interfaceelement, the second jaw rotates in one direction about the joint, andwhen the second drive interface element applies a drive in an opposingdirection the second jaw rotates in an opposing direction about thatjoint.